1. Field of the Invention
The invention relates to a bag produced from a thin pleated sheet provided with self-closing means.
2. Description of the Related Art
European Patent EP-0-631,560 describes packaging for containing loose products, produced from a thin sheet comprising asymmetrical pleats fixed at their ends, the pleated part being folded on itself perpendicularly to the direction of the pleats to form a simple base or a bellows-type base, leaving an opening whose edges are in line or offset. The pleated part is extended on each side by a non-pleated zone forming two walls which may be fixed to each other. This patent describes several methods of closing the packaging thus obtained:
a first method of closure relates to a bag comprising, on each side, a welding of the unpleated zones and one of the edges of which is sufficiently offset to be able then to serve as a flap when the bag is full; PA1 a second method of closure consists in extending a pleated zone laterally by a non-pleated zone of a length sufficient to produce a receptacle when the base is formed and the walls which constitute it are fixed at their ends, whilst the non-pleated part limiting the other end of the fold remains free. Closure is then obtained by unfolding the pleated part over the non-pleated part.
The first method of closure described above applies to a bag which is easily identifiable by the user, but requires the use of a locking means because the flap does not stay in place alone.
The second method of closure is self-locking, but its manipulation requires a manual manoeuvre which users need to learn.